The present invention relates to a portable telephone system for a mobile radio telephone set such as PDC or PHS, which enables a network and a mobile radio telephone set to be efficiently operated when a call is made to the mobile telephone set not placed in an incoming call enable state.
In recent years, there has been a rapid spread of a portable telephone set. The portable telephone set can make a call and receive a call from any place as long as it is within a service area. But manners of using it have begun to be questioned. The use of the portable telephone set is even prohibited in certain buildings such as hospitals or hotels.
Conventionally, as manners when entering the area prohibiting the use of the portable telephone set, power for the telephone set has been cut beforehand or an automatic answering service has been made effective, the automatic answering service being provided for proxy-receiving the voice of a call made to the portable telephone set in a network side. But it was necessary for any of these to be operated by own key operations.
FIG. 5 shows a sequence of operations when a call comes in to a portable telephone set held in a power OFF state or out of receivable bounds in a conventional potable telephone set.
Conventionally, when a power ON operation is carried out for the portable telephone set within a service area, a position registration process (501) of the telephone set is performed for a database used for position management and located in the network. In other words, a position registration request is made from the portable telephone set 51 to a position management server via a public base station, and the position registration server informs, after its registration, the portable telephone set 51 of its position registration reception.
It is now assumed that after the completion of position registration, a holder of the portable telephone set 51 moves indoors and performs a power OFF operation. Then, when call setting is made from a portable telephone set 52 (502), since it is impossible to understand the state of the portable telephone set 51, the network performs processing for calling the portable telephone set 51 from the base station where its position has been registered (503). However, actually since the portable telephone set 51 is not in a call receiving state, after a time-out, a voice message or the like indicating connection unable is sounded to the portable telephone set 52 (504).
FIG. 6 shows a sequence of operations when after the above position registration, a holder of a portable telephone set 61 moves indoors where the use of the portable telephone set is prohibited and sets an automatic answering mode in the conventional portable telephone set.
After the automatic answering mode has been set from the portable telephone set 61 (601), when call setting or a call setting reception is made by the portable telephone set 61 (602), as in the above case, since it is impossible to understand the state of the portable telephone set 61, the network performs processing for calling the portable telephone set 61 from the base station where its position has been registered (603). However, since the portable telephone set 61 is not in a call receiving state, after a time-out, the network recognizes setting of the automatic answering mode for the portable telephone set 61, connects with the potable telephone set 61 and sets a pass for storing voices in a message server.
Such a portable telephone system was disclosed in, for example JP-A-69999/1994. The portable telephone system of this publication is configured to automatically receive, by setting a predetermined mode beforehand, a call without giving a calling sound so as to transmit a message to an opposite party or record a message if the telephone set cannot answer an incoming call. This portable telephone system is operated under the condition of setting a mode by a user himself beforehand.
On the conventional portable telephone system, since it doesn't have any means for recognizing the power OFF state of the portable telephone set, the setting state of the automatic answering mode or the location of the potable telephone set (out of receivable bounds), inconveniences have occurred, for example a call incoming to the portable telephone set prohibited from use, and useless incoming call control performed by the base station for the portable telephone set not placed in a call receivable state.
Furthermore, a power supply for the portable telephone set must be switched OFF or the automatic answering mode must be set for stopping the use of the portable telephone set or the like in an area where its use is prohibited. Thus, to enter an area, for instance a building, where the use of the portable telephone set is prohibited, its holder must perform such an operation himself.